(1) Field of the Invention
The present invention relates to a routing apparatus and a routing method, in particular, to a routing apparatus and a routing method suitable for use when it is necessary to reserve a resource (for example, a resource relating to a communication such as a bandwidth and the like) at the time of communication in a communication network performing TCP/IP (Transmission Control Protocol/Internet Protocol) communication.
(2) Description of the Related Art
In order to furnish services strict with delay [for example, VOD (Video On Demand), voice service and the like] using IP over the Internet, it is necessary to secure a resource (bandwidth, mainly) for the communication service. To cope with it, there is a protocol for reserving a resource called RSVP (Resource Reservation Protocol) defined by IETF (Internet Engineering Task Force).
RSVP is a technique for securing a predetermined necessary bandwidth for a session (connection) established between a sender and a receiver of data (packet) in TCP/IP layer and assign it [guaranteeing predetermined QoS (Quality of Service)]. However, RSVP itself does not have a routing protocol. For this, an existing protocol is used in a routing (destination determining) process on data by a routing apparatus [namely, a so-called IP router or an ATM (Asynchronous Transfer Mode) switch or the like having a function equivalent to that of the IP router].
Namely, in terms of packet data for RSVP such as an RSVP message (request for securing a resource) or the like, the existing routing apparatus (routing method) determines the next packet transfer target (adjacent routing apparatus; route) on the basis of only an IP address given to the packet data, and performs a packet transferring process, like other ordinary packet data.
Since such the known routing apparatus (routing method) performs a routing on the basis of only an IP address, there is possibility of trying a routing for an RSVP message to an apparatus in which a bandwidth cannot be secured (or is hardly secured). A reason of this is that the present IP is designed for a dynamic, best effort apparatus (a network configured on the basis of a theory that guarantees a necessary bandwidth for a communication when there is a margin in the bandwidth, but does not guarantee when there is not a margin), and does not possess a function of considering a state of use of a resource (for example, an idle bandwidth in the case of bandwidth) in another apparatus that can be the next packet transfer target (adjacent routing apparatus).
For this, there is a possibility of frequently performing a routing to an apparatus in which a bandwidth requested by an RSVP message cannot be secured (or is hardly secured) in the above routing apparatus. In consequence, a resource (a rate of use of CPU or the like) in the network is wastefully consumed so that loss might be generated. As a result, there is a possibility of degrading serviceability such that a service (VOD service or the like) requested by the user cannot be provided.
In the light of the above problems, an object of the present invention is to provide a routing apparatus and a routing method, in which a routing process is performed in consideration of a state of use of a resource in the adjacent routing apparatus when a request for reserving a resource (communication resource) is received, whereby a wasteful routing is prevented at the time of resource reservation.
The present invention therefore provides a routing apparatus comprising a routing controlling unit for controlling transfer of a received packet data to an adjacent routing apparatus on a basis of destination information of the packet data, a first resource management unit for managing resource management information regarding communication resource in another routing apparatus that can be the adjacent routing apparatus, and a first determining unit for securing a communication resource upon receiving a packet data for a reservation request, and determining the adjacent routing apparatus on the basis of destination information given to the packet data and the resource management information.
The above first resource management unit may hold at least information in which routing information on another routing apparatus that can be the adjacent routing apparatus and use state information on the communication resource in the same are corresponded to each other as the resource management information. In such case, it is desirable that the above first determining unit is configured as a routing determining unit for reservation request for determining routing information for another routing apparatus in which a communication resource according to the packet data for a reservation request can be secured as routing information for the adjacent routing apparatus on the basis of the use state information, and the routing controlling unit controls the routing on the basis of the routing information determined by the reservation request routing determining unit.
The present invention also provides a routing method used in a communication network in which a plurality of routing apparatuses each handling packet data for a desired communication service comprising the steps of receiving a packet data for a communication resource reservation request; and carrying out a routing process for transferring the reservation request to a adjacent routing apparatus in consideration of at least a state of use of a communication resource in another routing apparatus that can be the adjacent routing apparatus.
According to the routing apparatus and the routing method of this invention, it is possible to perform a routing in consideration of at least a state of use of a communication resource in another routing apparatus that can be the adjacent routing apparatus when a reservation request for reserving use of a communication resource required to implement a desired communication service is received. It is therefore possible to largely decrease a possibility of performing a wasteful routing process to a routing apparatus in which a communication resource according to the above reservation request cannot be secured or is hardly secured, so that the communication resource is effectively used.
The above routing controlling unit may include a first resource management information creating/updating unit for creating or updating the resource management information on the basis of a record of securing a communication resource in another routing apparatus that was once the adjacent routing apparatus for past packet data for a reservation request.
It is thereby possible to automatically hold information on a recent state of use of a communication resource in another routing apparatus, thus easily grasp the recent state of use of a communication resource in the same.
The first resource management information creating/updating unit may comprise a first timer unit for measuring a first predetermined period from when the resource management information is created, a first information confirming unit for confirming whether or not resource management information held longer than the predetermined period exists in the first resource management unit on the basis of time-measuring information of the first timer unit, and a first information deleting unit for deleting resource management information in the first resource management unit when the first information confirming unit confirms that the resource management information held longer than the first predetermined period exists in the first resource management unit.
As above, the created resource management information is held for a predetermined period. When a similar reservation request is received within the predetermined period, a routing for the reservation request is performed on the basis of the created resource management information, so that a load of the routing is decreased, and a memory quantity required to hold information is decreased.
The above first resource management information creating/updating unit may comprise a first monitoring unit for monitoring whether or not a communication resource according to the packet data for a reservation request can be secured in the adjacent routing apparatus, a second information confirming unit for confirming whether or not resource management information corresponding to the adjacent routing apparatus exists in the first resource management unit when the first monitoring unit confirms that the communication resource cannot be secured in the adjacent routing apparatus, and a second information deleting unit for deleting the resource management information in the first resource management unit when the second information confirming unit confirms that the resource management information corresponding to the adjacent routing apparatus in which the communication resource cannot be secured exists.
When a communication resource according to the above reservation request cannot be secured in the adjacent routing apparatus, resource management information on that apparatus can be deleted. It is therefore possible to prevent an increase of a memory quantity because of holding unnecessary resource management information, and prevent an erroneous determination on the adjacent routing apparatus.
The present invention still also provides a routing apparatus comprising an interconnection controlling unit for controlling an interconnection to transfer a received packet data to an adjacent routing apparatus on the basis of destination information of the packet data, a second resource management unit for managing resource management information regarding a communication resource in another routing apparatus that can be the adjacent routing apparatus, and a second determining unit for securing a communication resource according to a reservation request upon receiving a packet data for the reservation request, and determining the adjacent routing apparatus on the basis of destination information given to the packet data and the resource management information.
The above second resource management unit may hold at least information in which interconnection information on another routing apparatus that can be the adjacent routing apparatus and use state information on a communication resource in the same are corresponded to each other as the resource management information. In such case, it is desirable that the above second determining unit is configured as a connection determining unit for reservation request for determining interconnection information for another routing apparatus in which a communication resource according to the packet data for a reservation request can be secured as interconnection information for the adjacent routing apparatus on the basis of the use state information, and the above interconnection controlling unit controls the interconnection on the basis of the interconnection information determined by the connection determining unit, for reservation request.
The routing apparatus according to this invention can control an interconnection for a reservation request in consideration of a state of use of a communication resource in another routing apparatus that can be the adjacent routing apparatus. It is therefore possible to ensure a sufficient service quality to a communication service strict with delay, and prevent a wasteful routing.
The above interconnection controlling unit may comprise an interconnection confirming unit for confirming whether or not the interconnection for the adjacent routing apparatus determined by the second determining unit is already secured, and an interconnection assigning unit for assigning the interconnection to a packet transferring process when the interconnection confirming unit confirms that the interconnection is already secured.
As above, when an interconnection for the adjacent routing apparatus is already secured, the interconnection already secured can be used in the packet transferring process. It is thereby possible to decrease a degree of necessity of securing a new interconnection each time a reservation request is received, thus largely contribute to a decrease a processing load of this routing apparatus.
The above interconnection controlling unit may comprise a second resource management information creating/updating unit for creating or updating the resource management information on the basis of a record of securing a communication resource in another routing apparatus that was once the adjacent routing apparatus for past packet data for a reservation request.
Accordingly, it is possible to create or update resource management information on another apparatus that was once the adjacent routing apparatus by a past reservation request on the basis of a record of securing a communication resource in the same. Therefore, information on a recent state of use of a communication resource in another routing apparatus can be automatically held, and a recent state of use of the communication resource in another routing apparatus can be readily grasped.
The above interconnection controlling unit may comprise a second timer unit for measuring a second predetermined period from when an interconnection for the packet data for a reservation request is established, an interconnection continuative securing unit for continuing securement of the interconnection until the second predetermined period is elapsed in the second timer unit, and an interconnection releasing unit for releasing the interconnection when the second predetermined period is elapsed in the second timer unit. In such case, the above second resource management information creating/updating unit may comprise a third information deleting unit for deleting created resource management information on the adjacent routing apparatus corresponding to the interconnection released by the interconnection releasing unit in the second resource management unit.
As above, an interconnection once secured is held for a predetermined period (second predetermined period). It is therefore possible to decrease necessity of securing an interconnection each time a reservation request is received, and it is unnecessary to continuously secure a wasteful interconnection. Accordingly, a load of the interconnection control can be further decreased, and the communication resource can be effectively used.
The above second resource management information creating/updating unit may comprise a second monitoring unit for monitoring whether or not a communication resource according to the packet data for a reservation request can be secured in the adjacent routing apparatus, a third information confirming unit for confirming whether or not resource management information on the adjacent routing apparatus exists in the second resource management unit when the second monitoring unit confirms that the communication resource cannot be secured in the adjacent routing apparatus, and a fourth information deleting unit for deleting the resource management information in the second resource management unit when the third information confirming unit confirms that the resource management information on the adjacent routing apparatus in which the communication resource cannot be secured exists in the second resource management unit.
When a communication resource according to the above reservation request cannot be secured in the adjacent routing apparatus, resource information on that routing apparatus can be deleted. It is therefore possible to prevent an increase of a memory quantity because of holding unnecessary resource management information, and an erroneous determination on the adjacent routing apparatus.
When the above communication resource is a bandwidth, it is possible to perform a routing process (or an interconnection control) in consideration of a state of use of a bandwidth in another routing apparatus. Accordingly, it is possible to largely lessen probability of performing a routing to an apparatus in which a bandwidth cannot be secured (or is hardly secured) in response to a reservation request, thus certainly prevent a wasteful routing (an interconnection control) from being performed.